1. Field of the Invention
This invention relates to electromagnetic devices used to generate mechanical work output in response to an electrical input to one or more electromagnet coils. In particular, it relates to a class of devices using permanent magnets, in conjunction with the internal magnetic field energy of a ferromagnetic material, to affect efficient electromechanical energy conversion.
2. Description of the Prior Art
Actuators for converting electrical energy to mechanical energy have long been known and have been called solenoids, electromagnets, force motors, torque motors and various other names. The most common linear or rotary solenoid produces mechanical energy when an internal air gap decreases in length. Less common are the devices described in U.S. Pat. Nos. 3,870,931 and 4,097,833, in which an air gap of variable area converts electrical to mechanical energy. Unlike prior art, the object of the present invention is to utilize magnetic fields internal to a ferromagnetic core, with no substantial variation in either gap length or area. Another object is to utilize the large number of ferromagnetic material formulations which are available. Still another object is to customize the force or torque output by varying core characteristics. Other objects and advantages will become apparent from the following description.